An Egyptian appeals court on Sunday overturned Hosni Mubarak's life sentence and ordered a retrial of the ousted leader in the killing of hundreds of protesters, a ruling likely to further unsettle a nation still reeling from political turmoil, and to complicate the struggle of his Islamist successor to assert his authority.

The court's decision put the spotlight back on the divisive issue of justice for Mubarak and his top security officers, who were also ordered retried, two years after the revolution that toppled him.

The ruling poses a distraction for President Mohammed Morsi as he tries to restore law and order, grapple with a wrecked economy, and deal with the bitter rivalry between his camp of Islamists and an opposition led by liberals and secularists.

A retrial is virtually certain to dominate national headlines, attracting attention away from a crucial election for a new house of deputies about three months from now. Morsi and his Islamist allies are determined to win a comfortable majority in the new chamber, allowing them to take the helm of the most populous Arab nation.

The ailing 84-year-old Mubarak is currently being held in a military hospital and will not walk free after Sunday's decision. He remains under investigation in an unrelated case.

If convicted, Mubarak could face a life sentence or have it reduced. He could also be acquitted. Under Egyptian law, a defendant cannot face a harsher sentence in a retrial, meaning the former leader cannot face the death penalty.

The Court of Cassation did not immediately disclose its reasoning, but legal experts said the appeal was granted over a series of procedural problems in the conduct of the original trial.

The ruling had been widely expected. When Mubarak was convicted in June, the presiding judge criticized the prosecution's case, saying it lacked concrete evidence and failed to prove that the protesters were killed by the police.

Mubarak's defense lawyers had argued that he did not know of the killings or realize the extent of the protests. But a fact-finding mission recently determined that he watched the uprising against him unfold through a live TV feed at his palace.